/*
* Copyright (c) 2002-2009 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.graphdb;
/**
* Defines relationship directions used to when getting relationships from a
* node or when creating traversers.
* <p>
* A relationship has a direction from a node's point of view. If a node is
* the start node of a relationship it will be an {@link #OUTGOING}
* relationship from that node's point of view. If a node is the end node of
* a relationship it will be an {@link #INCOMING} relationship from that
* node's point of view. The {@link #BOTH} direction is used when direction
* is of no imporance, such as "give me all" or "traverse all" relationships
* that are either {@link #OUTGOING} or {@link #INCOMING}.
*/
public enum Direction
{
/**
* Defines outgoing relationships.
*/
OUTGOING,
/**
* Defines incoming relationships.
*/
INCOMING,
/**
* Defines both incoming and outgoing relationships.
*/
BOTH;
/**
* Reverses the direction returning {@link #INCOMING} if this equals
* {@link #OUTGOING}, {@link #OUTGOING} if this equals {@link #INCOMING} or
* {@link #BOTH} if this equals {@link #BOTH}.
*
* @return The reversed direction.
*/
public Direction reverse()
{
switch ( this )
{
case OUTGOING: return INCOMING;
case INCOMING: return OUTGOING;
case BOTH: return BOTH;
default: throw new IllegalStateException( "Unknown Direction " +
"enum: " + this );
}
}
}